The technique of nuclear magnetic resonance (NMR) has been used to study the disposition of fluorinated deoxyglucose in intact rats, of 6-fluorodopamine in nerve microsacs, and of difluoroserotonin, carbon-13-labelled serotonin and lithium in platelets from rabbits, pigs, cows, and humans. Amines inside storage vesicles and in extra-vesicular sites in each tissue type have unique motional properties and chemical-shift parameters, which suggest that each tissue possesses unique storage mechanisms.